Many automotive fuel systems utilize an in-tank electric fuel pump for supplying fuel from the fuel tank to the engine. It is desirable in many fuel systems for fuel pump output pressure to vary according to engine fuel demand. This is accomplished by modulating the supply voltage through an electronic drive module to the electric motor of the fuel pump. Typically, the drive module receives a signal from a remote pressure sensor and supplies a pulse width modulated current to the pump motor having a duty cycle that varies so as to vary and maintain the necessary pump speed for supplying proper fuel pressure to the engine. Usually, the drive module includes a relatively large heat sink to dissipate to the ambient atmosphere heat generated by producing the pulsed current.
In many present fuel systems, the electronic drive module is mounted remote from the fuel pump and tank and supplies a variable electronic signal to the fuel pump electric motor through electric wires. The drive module is normally installed at the automotive assembly plant on a vehicle under-body or in a wheel well which necessitates added labor, packaging space and fasteners for mounting the module. The electric wires must be routed from the drive module to the fuel pump requiring additional labor, packaging space and fasteners to mount the wires on the vehicle body. These wires also act as an antenna for radio frequencies causing interference with the proper function of the electronic drive module.
As disclosed in U.S. Pat. Nos. 5,120,201 and 5,148,792, the electronic drive circuit components may also be constructed as a permanent, integral part of the fuel pump assembly. When the fuel pump or the electronic drive circuit fails, both would be replaced. This creates unnecessary expense and waste by requiring replacement of functional equipment.